Method for producing an insulating pack for an insulating part

ABSTRACT

The invention relates to a method for producing an insulating pack ( 10 ), according to which a stack ( 9 ) of metallic lamellae is cold-welded simultaneously along a predefined contour and separated from a remaining area. The insulating pack produced according to the invention preferably has a plurality of knobbed and/or perforated aluminium foils ( 12, 14, 16 ) and at least one stretch film ( 18 ) and is characterized by a narrow welding seam ( 20 ) extending along the edge. The insulating pack can be used as an insulating part on its own or loosely inserted into an additional supporting or covering layer. Such insulating parts can be configured in an acoustically active manner and are used in the motor industry, machine industry and/or electronic or computer industry. Means for carrying out the method provided for in the invention provide for the use of a cutting blade with two cutting flanks. A preferred version of the cutting blade has cutting flanks inclined at different angles and can be configured as a rotary blade.

This application is a 35 U.S.C. § 371 of International ApplicationPCT/CH98/00551 which is a continuation of application Ser. No.60/070,188 filed Dec. 30, 1997, now abandoned, entitled Laminated Shieldand a Method of Making the Shield.

FIELD OF THE INVENTION

The present invention relates to a method for manufacturing aninsulating pack for an insulation part in particular for a heat shield,the insulating pack having at least two stacked metallic sheets; to aninsulating pack manufactured therewith in particular a heat shield, withseveral stacked, metallic sheets; as well as to a separating tool forcarrying out the method, the separating tool having two separatingflanks, the separating flanks having different angles to a contactsurface.

BACKGROUND OF THE INVENTION

In the motor vehicle industry, as well as in other technical fields,there exists a requirement for thin thermic insulation parts which maybe adapted to their application purpose in a simple manner. It istherefore desirable to be able to economically manufacture suchinsulating parts, in particular thin heat shields, which may be broughtinto the desired shape in a simple manner. Known insulation parts areconstructed of a stack of several aluminium foils or aluminium sheetmetals. Such insulation parts find an increasing application with heatshields for vehicles.

Such a heat shield is for example disclosed in U.S. Pat. No. 5,011,743and its corresponding application WO 91/10560. These documents disclosea foil package which comprises heat-conducting zones, so called heatsinks, and heat-insulating zones. In particular these foils compriseembossings or naps which result in the stacked foils being distancedfrom one another. The individual foils may be connected to one anotherin a hermetically sealed manner, by which means the enclosure of a gase.g. xenon is made possible. In a further embodiment of this inventionthe individual foils are perforated for improving the acousticeffectiveness. The edge regions of this foil package are in practicepressed together with a considerable pressure force and are cut inseparate method steps, and are subsequently crimped, heat sealed ormechanically connected. With these known foil packages, and due tomechanical strain which is, for example, exerted during transport orduring operation, the foils may separate again in the connection region.

The above described insulating pack or heat shield has a number ofdisadvantages. One disadvantage which becomes obvious to the man skilledin the art lies in the fact that heat flows through the heat sinkregions onto the other side of the insulation part and on account of therelatively wide border regions, the proportion of the effectiveinsulation surface on the whole heat shield is undesireably reduced.Furthermore, the conventional manufacture of such heat shields has shownto be complicated with respect to tooling. On account of the sharppoints occurring when using stretch sheet metal and the high risk ofinjury to personnel related to this, such stretch sheet metal is notapplied.

SUMMARY OF THE INVENTION

It is therefore the aim of the present invention to provide aninexpensive method, i.e. simple with respect to tooling, formanufacturing an insulating pack or pad for an insulation part or a heatshield, which permits in as few operating steps as possible aprocessing-friendly and safe heat shield to be manufactured from a stackof metallic sheets, wherein the individual sheets of this stack in theiredge regions are firmly connected to one another, without at the sametime heat sinks being formed.

In the following metallic sheets are to be understood in general beingextended metal parts. These extended metal parts may have differingthicknesses, may be perforated or have a particular structure. Inparticular these are to be understood as perforated (having holes orbeing fissured) or unperforated foils, thin metal sheets or metalsheeting, foils in the form of stretch metal grids, stretch foils, metalknittings, metal weavings, metal tissue or similar surfaced structures.These sheets may also be coated or comprise honeycomb-like deformationpatterns (honeycomb-sheet-metal) or may be shaped in a different manner,in particular may be napped.

This aim is achieved according to the invention by cold welding ormetallurgically connecting, with the aid of a separating knife, apredetermined region of stacked metallic sheets along a contour of theregion whilst forming a continuous welding seam and simultaneouslyseparating the stacked metallic sheets from a residual region, and inparticular by a method for manufacturing an insulating pack with a stackof several metallic sheets, which may be embossed and/or perforated, andwith this method the individual sheets of the stack are continuouslycold-welded in their peripheral region and at the same time areseparated from the residual material. Cold-welding in the following isto be understood as a metallurgical connection or bonding which isachieved by means of a plastic deformation of two or more neighbouringsheets, and with this deformation the metallic material of neighbouringsheets integrally connects. With aluminium such a connection may beachieved when the material is compressed for example by approx. 75%.

With the method according to the invention at least two metal sheets arestacked, wherein individual sheets may be embossed. According to theinvention, the stack produced in such a manner is cold-welded along apredetermined contour and at the same time is separated from the cuttingwaste. This is preferably achieved with a mould press equipped with asuitable separating tool. It is to be understood that this cold-weldingof the stack periphery and the separation of the individual sheets ofthe stack may also be accomplished with other suitable separating tools.

Furthermore with this cold-welding method an insulating pack consistingof a multitude of differing (for example napped, holed, or grid-like)sheets, foils or sheet metals may be manufactured. With the applicationof stretch metal sheeting, edges may be produced which do not have anysharp points. The method according to the invention furthermore permitsinsulating packs to be deformed in a suitable manner. In particular, theapplication of stretch-metal-like sheets, in contrast to s perforatedsheets, has proven to be particularly advantageous, since such stretchmetal sheets are lighter, more easily deformable and tear less easily.Furthermore the acoustic effectiveness of these stretch-metal-likesheets may be controlled or adjusted in a simple manner by the formationof differently large openings.

It is further the aim of the present invention to provide anacoustically effective insulating pack, in particular a heat shield witha stack of metallic sheets, which overcomes the above citeddeficiencies, wherein the individual sheets of this stack in their edgeregions are firmly connected to one another, without at the same timeheat sink regions being produced. Furthermore an insulating pack is tobe provided which may be deformed in a simple manner without at the sametime becoming damaged or separating during transportation or use.

According to the invention this aim is achieved by an insulating pack orpad with several stacked, metallic sheets, having a continuous cold-weldseam along its contour, and in particular by an insulating pack in whichthe individual sheets of the stack are cold-welded to one another alongtheir common edges. In one preferred embodiment of this insulating packthe cold-weld seam is approx. 0.3 mm wide. In another particularembodiment the insulating pack comprises at least one stretch sheetmetal. In another particular embodiment the insulating pack is providedwith at least one fold line in order to permit a strong deformation ofthe whole insulation package in a simple manner; and in yet anotherparticular embodiment at least one of the metallic sheets of theinsulating pack is napped and/or perforated.

In a preferred embodiment of the present invention the insulating packor heat shield comprises a plurality of aluminium foils which arecold-welded to each other along their respective edges. With thesecold-welded foils a peripheral connection is produced which issubstantially more stable than the embossing or adhesing methods whichare disclosed in the state of the art, for example in U.S. Pat. No.5,011,743. The inventive insulating pack is welded only along its edgeor peripheral regions, which ensures good heat insulating propertiesover the entire inner region.

In a preferred embodiment the insulating pack comprises a multitude ofstacked metal foils, as well as a carrier sheet metal and a cover foilor a cover sheet metal. With this embodiment the carrier sheet metalconsists of a stretch metal or a perforated sheet metal. In a particularembodiment the invention comprises a foil stack, with which theindividual foils are perforated and are fastened on a perforated carriersheet metal. According to the invention with all these embodiments atleast the foils of the foil stack are cold-welded to one another. It ishowever to be understood that the foils of the foil stack may also becold-welded directly to the carrier sheet metal and/or to the coverfoil.

It is an additional aim of the present invention to provide suitablemeans for carrying out the method according to the invention.

According to the present invention this additional aim is achieved byuse of a separating knife, and in particular by use of a separatingknife, whose separating flanks preferably inclined to a differing degreeto the separating plane. In a particularly preferred embodiment a firstseparating flank is at an acute angle of approx. 60° to the contactsurface and a second separating flank is at a less acute angle ofapprox. 25° to the contact surface. A further embodiment of thisseparating knife is formed as a round knife.

By applying a separating tool it is possible to produce such acold-welding along the edges of the stack of metallic sheets. In thisway the individual sheets are simultaneously connected to one anotherand brought into a special contour.

A particularly advantageous formation of the separating tool comprises aseparating knife which has an acute angle of preferably 60° between afirst separating flank and the cold-welding plane and which separatingknife has an acute angle of preferably 25° between a second separatingflank and the cold-welding plane in such a manner that between the twoseparating flanks of the separating knife there is formed an obtuseangle of, for example, 95°.

The inventive application or use of cold-welding has proven to beconsiderably advantageous with respect to known methods for connectingthe individual sheets of a stack, inasmuch as such cold welding can becarried out considerably more simply and quickly, as well as moreeconomically and safely. When this cold-welding method is combined witha separating step, the number of method steps for manufacturing suchinsulating packs can be considerably reduced as compared to conventionalmethods (in particular as compared to complicated crimping methods).

The insulating pack according to the invention does not have anydisadvantageous heat sinks but rather comprises an extremely narrowregion in which the individual sheets have an integral connection toanother and thus in a reliable and long lasting manner. Furthermore, theinsulating packs manufactured according to the invention, and even whenusing stretch-metal-like sheets, do not have any sharp points and may befolded into any desired shape at their fold lines, without at the sametime tearing, breaking or coming apart at their edge regions.Furthermore the geometric course of the cold-welded connection may beshaped in any manner, i.e. as a serpentine line or complementarily tothe geometric course of the edge region of a neighbouring insulatingpack, and in particular a heat shield which is to be manufactured fromthe same sheets. In particular, it is thus possible to minimise thecutting waste during manufacture of these insulating packs.

The above mentioned subject-matter of the invention and furtherformations, advantages and characteristics of the invention in thefollowing are explained by way of example by way of the drawings or maybe evidently deduced from the following description of the preferredembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows in a perspective view one embodiment of a stack of metallicsheets connected according to the invention;

FIG. 2 shows a view of a stack according to the invention in crosssection, during the cold welding process;

FIG. 3 shows a plan view of a stack which has been cold-welded andseparated according to the invention;

FIG. 4 shows a view of a particular shape of an insulation packageaccording to the invention;

FIG. 5 shows means for carrying out the method of manufacturing aninsulating pack according to the invention; and

FIG. 6 shows further means for carrying out the method according to theinvention.

DETAILED DESCRIPTION

In FIGS. 1 to 3, in which the same components are provided with the samereference numerals, a multi-layered insulating pack 10 for an insulationpart or heat shield is shown. Here it is to be noted that in the Figuresthe individual sheets are not shown to scale. The insulating pack 10 isapplied preferably to the lower floor region of vehicles, and inparticular as an acoustically effective heat shield. Such insulatingpacks may comprise additional carrier, intermediate or cover layers.With known embodiments, perforated carrier sheet metals, knittedintermediate layers or flame sprayed cover layers are used. Insulationparts are also known in which the insulating packs are loosely arrangedbetween a carrier sheet metal and a cover foil.

The insulating pack 10 comprises a multitude of metallic sheets, whichin the formation shown in FIG. 1 comprise an upper embossed or nappedfoil 12 with naps 24, an embossed intermediate foil 14, likewise withnaps 24, a flat or unembossed foil 16 and a stretch foil 18. Thisstretch foil may have carrier functions and is easily deformable.Instead of such a stretch foil 18 also a perforated plate of a knowntype may be provided. All sheets of this insulating pack 10 have in theplan view the same contour and are connected metallurgically to oneanother, i.e. with an integral connection at their common edges by wayof a cold-welding process. This metallurgic connection leads to acircumferential, continuous integral welding seam 20.

In FIG. 1 it is made clear that by way of the cold welding of theindividual sheets there is formed a fine welding seam 20 which does nothave sharp edges and thus also permits the use of stretch-metal-likesheets or thin stretch sheet metals. This welding seam 20 is approx. 0.3mm wide and differs significantly from the known, approx. 7 mm widesqueezed, compressed or crimped edges.

The insulating packs shown in FIGS. 2 and 3 have essentially the samesequence of foils as in FIG. 1. The foils of this insulating pack 10 inFIG. 3 all comprise a multitude of perforations 30, in order thus toimprove the acoustic effectiveness of the insulating packs. In theembodiments shown in these FIGS. 2 and 3, the insulating pack 10comprises a recess 31 arranged in the inside for purposes of securingthe same, the edge 32 of which is formed by a weld seam. With the methodaccording to the invention the recess 31 is produced by creating acold-welded seam 20 and simultaneously separating the respective sheetregions A, B. In a preferred embodiment the insulating pack 10 issimultaneously provided with predetermined fold lines 34, consisting ofcontinuously running notches and/or partially running incisions.

According to the invention the individual sheets are selected from amaterial which, when pressure is applied, may be plastically deformed insuch a manner that the individual layers metallurgically connect underpressure. As a working material it is preferable to use aluminium with athickness of approx. 50 μm, although also other metals or alloys, ordifferent thicknesses may be used, such as for example steel sheetmetal, copper or gold. Accordingly, in the described embodiment thestretch-metal-like foil or the perforated carrier sheet metal ispreferably made of aluminium.

The embossed or napped foils 12 and 14 may be manufactured in aconventional shaping roller, wherein by way of the embossing a multitudeof naps 24 are formed as are shown in FIG. 2. These naps 24 space theindividual foils from one another and lead to an insulating andacoustically effective air space between the individual foils.

The stretch-metal-like foil 18 and the embossed or napped foils 12 and14 separate the individual foils from one another in a manner such thatany heat transfer which occurs on account of a direct metallic contactis minimised and thus a good heat insulation is achieved. The use of astretch foil 18 or a perforated plate leads to an improvement of theacoustic absorption capability of the insulating pack.

Although the insulating pack 10 with foils 12, 14, 16 and 18 is shown ina certain arrangement or sequence, it is to be understood that otherarrangement combinations are evident to the man skilled in the art. Forexample, additional embossed foils, additional stretch foils orintermediate layers of a known type may be used. It is within the skillof the expert to so select these individual sheets and their perforationopenings or their thickness that the required properties may be used inan optimal manner.

Cold-welding methods are essentially known to the man skilled in the artbut, however, are not known for use in mould pressing tools. In themethod according to the invention the metal sheets to be metallurgicallyconnected are exposed to such a high pressure that their surface layersenter into an integral connection with one another. In a preferredembodiment of the present invention, a suitable steel tape acting as aseparating knife 51 and having a width of approx. 1 mm is applied into amould pressing tool. This separating knife 51 is inserted in such amanner that it follows the desired contour of the insulating pack to bemanufactured. For producing a cold welding seam 20 according to theinvention, and as can be seen from FIG. 2, the separating flanks 52 and53 of this separating knife 51 are arranged preferably asymmetrically.In particular, the separating flank 53 which faces the insulating pack10 to be manufactured runs at a narrower angle than the separating flank52 facing away from the insulating pack 10 to be manufactured. Theresult of this geometric arrangement of the separating flanks is, thaton closing the mould pressing tool the metallic sheets lying under theseparating flank 53 are metallurgically connected or bonded to oneanother and are separated in the region of the separating edge 54. In ananalogous manner, tool parts 56 and 57 can be provided such that withthese tool parts a hole 31 is cut out of the insulating pack 10 and, atthe same time, the edge of the hole is cold welded to form acircumferential welding seam 20. A suitable pressure force lies in theregion of 1.7 kN per 10 mm edge length. This corresponds to 17 tonspressure force on an edge length of 1 meter. With a form pressing toolof approx. 1600×900 mm², with which several insulating packs having atotal edge length of about 10 to 20 m may be manufacturedsimultaneously, a pressure force of up to 340 tons is thereforerequired. This pressure force may be considerably reduced by increasingthe closing speed of the press, which can also increase the longevity ofthe separating knife. In order to be able to automatically decollatesurface portions A, B which have previously been separated from oneanother, a pressurised air tool of any known type may be used.

The insulating packs manufactured in such a way may be used as anacoustically effective heat shield and in particular are mounted in theregion between hot vehicle parts (catalytic converter, exhaust pipe,etc.) and the vehicle floor. It is to be understood that theseinsulating packs may also be arranged between the engine compartment andthe passenger compartment.

FIG. 4 shows a metal sheet stack 9 which has been welded and separatedaccording to the invention, and which has two fold lines 34 a and 34 b.This stack comprises a region A, which is not yet decollated, i.e. whichstill rests in the residual region B which is to be removed. During themanufacture of an insulating pack 10 this residual region B remains astrimming waste. With this metal sheet stack 9 a key-hole-shaped regionis separated along a weld seam 20. This particular shaping permits thefinished insulating pack to be inserted or slipped over a lead which hasalready been mounted in the vehicle, such as, for example, an electriccable or a hose. By way of a Z-like folding of the insulating pack 10along the fold lines 34 a, 34 b, the insulating pack 10 forms ahole-shaped opening through which the mounted lead may be guided.Depending upon the intended use of the insulating pack the expert mayshape other suitable fold lines and package shapes, in particulargroove-shaped or tubular coverings. The use of stretch-metal type ornapped metal sheets is suitable in particular for such extremelydeformed insulation parts.

In the following, and with the aid of FIGS. 5, 6 a and 6 b, suitablemethods and means for manufacturing insulating packs are described, inwhich a selected metal sheet stack 9 is cold-welded along apredetermined contour and at the same time is separated.

In a preferred embodiment as is shown in FIG. 5, the metal sheets orfoils selected and napped in a suitable manner are stacked on oneanother and inserted into a form pressing tool. This form pressing toolcomprises a lower hard forming half 50 and an upper forming half havinga separating knife 51. The separating knife 51 is formed in a particularmanner in order to weld and separate an inserted metal sheet stack in amanner according to the invention. This separating knife comprisespreferably a first separating flank 52 which with the contact surface 55formed by the lower hard forming half 50 forms an acute angle 91,preferably of 60°. The separating knife 51 also comprises a secondseparating flank 53 which together with the contact surface 55 forms anacute angle 93, preferably of 25°. The first and the second separatingflanks form a separating edge 54. It is to be understood that forcarrying out the method according to the invention also a separatingknife with symmetrically arranged flanks being inclined at 45° to thecontact surface may be used.

In the method according to the invention the separating knife is pressedon the contact surface 55 such that the sheets lying therebetween areplastically deformed and thereby metallurgically connect or bond. Withthis plastic deformation the metallic material yields away from theregion of the separating flank 53 and flows between the separating flank53 and the contact surface 55. With the impinging of the separatingknife 51 onto the lower hard forming half the material thus welded isseparated along the separating edge 54.

FIG. 6a schematically shows particular means for carrying out the methodaccording to the invention. With this, instead of the lower forming halfa suitable hard roller 40 is used, which is rotatable about an axis 94.With this arrangement, instead of the linear separating knife 51 a roundor disk-shaped separating knife, or round knife 41 is used, which isrotatable about an axis 95 and whose separating flanks 42, 43 orseparating edge 44 are bent in an analogous manner. This embodimentpermits the present method for cold-welding and separating insulatingpacks to be automised in a simple manner.

In FIG. 6b a further possible embodiment of a separating means forcarrying out the method according to the invention is schematicallyshown. This also comprises a round knife 41 whose separating flanks 42,43 are formed preferably asymmetrically. In this embodiment the roundknife 41 is pressed onto a plane, hard base 50.

It is to be understood that the insulating part according to theinvention may not only be used in the vehicle industry, but generallyalso as an insulating pack in the engineering industry for insulatingheat and noise producing machines, in heat and cooling technology or inthe computer or electronics industry.

What is claimed is:
 1. A method for manufacturing an insulating pack foran insulation part, said insulating pack comprising at least two stackedmetallic sheets, comprising the following steps: defining a desiredfirst region of stacked metallic sheets to form the insulating pack;cold welding or metallurgically connecting each of the stacked metallicsheets to another of the stacked metallic sheets along a contour of saidfirst region between first and second halves of a separating tool, thefirst half having a separating knife having two asymmetric separatingflanks, said separating flanks being disposed at different anglesrelative to a contact surface of the second half; forming a continuouswelding seam; and simultaneously separating said first region from aresidual region of said stacked metallic sheets.
 2. A method accordingto claim 1, further comprising simultaneously providing the insulatingpack with fold lines in the form of continuously running notches orpartially running incisions.
 3. A method according to claim 2,characterised in that, several complementarily contoured metallurgicallyconnected insulating packs are manufactured simultaneously from thestacked metallic sheets and simultaneously separated along a commoncutting line in order thus to minimize an amount of residual material.4. An insulating pack manufactured according to the method of claim 1,comprising: a plurality of stacked metallic sheets; a continuouscold-weld seam along a contour of a first region thereof that connectseach sheet of said plurality of stacked metallic sheets to another ofsaid plurality of sheets; and a residual region opposite said firstregion and separated therefrom on a side of a cutting line defined bysaid cold-weld seam, said residual region having an un-welded edgeadjacent to said cold-weld seam.
 5. An insulating pack according toclaim 4, characterised in that the cold-weld seam is approximately 0.3mm wide.
 6. An insulating pack according to claim 4, characterised inthat said insulating pack further comprises at least one stretch sheetmetal.
 7. An insulating pack according to claim 4, characterised in thatsaid insulating pack further comprises at least one fold line.
 8. Aninsulating pack according to claim 4, characterised in that at least oneof the metallic sheets is napped or perforated.
 9. A separating tool forcarrying out the method according to claim 1, characterised in that saidseparating tool comprises a separating knife with two asymmetricseparating flanks, said separating flanks having different angles to acontact surface of a lower forming half of said separating tool.
 10. Aseparating tool according to claim 9, characterised in that theseparating knife is a circular, disk-shaped knife.
 11. The methodaccording to claim 1 wherein said step of separating said first regionfrom said residual region occurs in a portion of said residual regionlying between a first separating flank and said contact surface.
 12. Themethod according to claim 1 wherein said step of cold welding ormetallurgically connecting occurs in a portion of said first regionlying between a second separating flank and said contact surface. 13.The method according to claim 1 wherein said insulating pack is a heatshield.
 14. The method according to claim 1, further comprisingsimultaneously providing the insulating pack with fold lines in the formof continuously running notches and partially running incisions.
 15. Themethod according to claim 4 wherein said insulating pack is a heatshield.
 16. An insulating pack according to claim 4, characterised inthat at least one of the metallic sheets is napped and perforated. 17.The separating tool as claimed in claim 9 wherein a first separatingflank lies at an acute angle of approx. 60° to the contact surface and asecond separating flank lies at a less acute angle of approx. 25° to thecontact surface.
 18. The separating tool as claimed in claim 10, whereinthe separating knife is rotatable about an axis.